CSCE 315 Lecture 20

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Testing

if (cond1) {
    x = a;
} else {
    x = b;
}

if (cond2) {
    y = x+1;
} else {
    y = x+2;
}

if (cond3) {
    z = c;
} else {
    z = d;
}

• Logic Coverage would have 8 conditions (TTT, TTF, TFT, TFF, FTT, FTF, FFT, FFF)
• Data flow would have 4 (all defined-used paths: (TTT, TFF, FT?, FF?)
• Structured Basis would have 2 (TTT, FFF)

Test case design

If you don't know the code,

• Boundary analysis still applies
• Equivalence partitioning (don't create tests that do the same things
• Bad data (too much/little data, wrong kind, uninitialized data)
• Good data (min/max/middle, backward compatability)

Test Automation

Running tests by hand is not appropriate Should do a lot of tests

Regression Testing

Find anything that has been broken by "fixing" something else Save old test cases.

Stup Routines

• Return standard data
• Burn cycles to simulate a long computation
• etc.

Test Harness

Calls the routine being tested:

• fixed input
• interactive input
• file-based input
• command-line argument input

Data Generators

Make a lot of data automatically (a lot more than by hand)

System Perturbers

• Reinitialize memory to something other than 0 to fix uninitialized variable errors.
• Rearrange memory locations to find out-of-bounds errors
• Memory bounds checking
• System failure simulation

Mock Objects

Setting up a dummy service.

Test-Driven Development

1. Write test
2. Run test (should fail)
3. Write code
4. Run Test (should pass)
5. Refactor
6. Run test (should still pass)
7. Repeat

Refactoring

• Clean up your code.
• Having a test suite can make sure that refactoring won't break your code.

Common Operations

• Extract Class
• Extract Interface
• Extract Method
• Replace type with subclasses
• replace conditional with polymorphic objects
• Form template
• Introduce "explaining" variable
• Replace constructor with "factory" method
• Replace inheritance with delegation
• Replace magic number with symbolic constant
• Replace nested conditional with guard clause.